'Is it a cop-out to blame a voice in my head, as if that's not me, a different person who is the Hyde, or should I take responsibility for my own mind?'
This is an extremely good and interesting question. Let's first of all make a distinction between the physical brain, the computer processor that produces and processes thoughts, and the mind, as consciousness and will.
There is a part of the brain that gets triggered when I drink and sends an overriding command to the decision-making centre, which says: DRINK MORE! This is a physical mechanism. I've discussed this at depth with a contemporary chief physician of a major alcohol treatment clinic in Germany. He confirmed for me and expanded on the idea presented in the chapter 'The Doctor's Opinion' that alcoholics respond differently to alcohol on a physical level. The only solution is abstinence. Eventually that part of the brain becomes, as it were, 'taped off'.
There is another part of the brain that will always view alcohol as desirable. In untreated alcoholics, this part of the brain is very powerful and also sends the overriding command to the decision-making centre, which says: DRINK! ... despite the dire consequences.
My take is that I am not the producer of my brain's thoughts; I am the decision-maker, who gets to pick which thoughts to reject, which thoughts to believe, which thoughts to engage and interact with, which thoughts to act on, etc.
That's where my responsibility lies, as the decision-maker between the thoughts (or, if you will, the voices).
What recovery does is restore the sanity and strength of that decision-maker to the point where the 'DRINK!' bit of the brain no longer sends commands up to the decision-making centre; it now sends only suggestions, which appear laughable. For me to drink, given my history, would be ridiculous. Also, that part of my brain is largely asleep. It gets activated only if I get spiritually out of whack, in practice when I feel separate from others due to unforgiveness, unfinished business, and selfishness.
So, to summarise, I'm not responsible for the thoughts my brain shoots at me. I'm also not responsible for the fact that my decision-making centre, when I got to AA, was fatally weakened, but I am responsible for accessing the help to restore me to a sane way of thinking and behaving.
Footnote: I'm also responsible for clearing up the mess. If I knock over a table and everything goes on the floor, I have to clear it up, whether it was an accident or on purpose.